Since I remove the DRM from any books I buy, I don't want to bother with registering a reader and having to connect it to the bookstore via WiFi or the computer.

For example, I've had 3 different Sony readers, and after the first one, I never bothered to register them with Sony. I move liberated ebooks to it or an SD card using Calibre.

I was at B&N looking at a Touch Glow. But the person in the store said you can not use it until it's registered - and the registration HAS to be completed via WiFi.

I was looking on Kobo's page about its Glo, and it reads the same, except it must be done via USB cable (you have to set it up using the Reader Desktop software?) Is that true, or do they just say that because they assume everyone wants/needs to register? Does anyone use their Kobo by sideloading DRM-free books exclusively without ever registering it or connecting to the Kobo servers?

The Kobo Glo can be set-up using WiFi or via the USB cable and the Kobo desktop app. You need to register it, then it downloads the latest firmware and installs that. After that, you can turn the WiFi off and never connect again unless you want to update the firmware.

Most of my books are sideloaded. For at least the first six months, this was the only way I put books on the device except a couple of free books from Kobo to see how that worked. But, I have been buying books from the Kobo shop recently. It is convenient and with the promo codes that are around, it is usually cheaper than other shops. They supply both their own kepub format that can download over WiFi, or Adobe ePub that you can handle yourself.

There is some info in the Kobo forum about sidestepping the registration process, but I haven't tried it.

I was at B&N looking at a Touch Glow. But the person in the store said you can not use it until it's registered - and the registration HAS to be completed via WiFi.

...

You can skip the registration on the Nooks but people who have done so often report high battery drain. And if you do decide to register, you can skip the step that asks for credit card information and just leave wi-fi off the rest of the time, which is nice. If you want firmware updates, those can be sideloaded.